Field geospatial data were collected using a handheld
GPS receiver using Wide Area Augmentation System
(WAAS) correction. The spatial coordinate for the
center of each site was used to obtain ortho-rectified
digital aerial imagery (Appendix A). We digitized the
habitats surrounding each study site to a radius of 3.5
km using ARC GIS 9.1 (ESRI 2005). These aerial
images differed temporally, representing images captured
between 1998 and 2006. Land use changes between
the image date and study period were recorded by
ground-verification in June–August annually, with
corrections made during the digitization process. At
the same time we also determined the specific land cover
present within all areas of each landscape (Appendix B).
Some locations included polygons that were not visible
from a roadway and permission to access private lands
could not be obtained. These polygons were given a
value of zero and were excluded from further analysis.
The area of each site that could not be identified varied
from 0% to 2%.